{	Problem: http://codeforces.ru/problemset/problem/13/A
	Verdict: Accepted
}
var i,n,g,t:longint; res:int64;
procedure swap(var a,b:int64);
var t:int64;
begin
t:=a;
a:=b;
b:=t;
end;
function gcd(a,b:int64):int64;
begin
if a<b then swap(a,b);
while b>0 do begin
  a:=a mod b;
  swap(a,b);
end;
result:=a;
end;
begin
readln(n);
res:=0;
for i:=2 to n-1 do begin
  t:=n;
  while t<>0 do begin
    inc(res,t mod i);
    t:=t div i;
  end;
end;
g:=gcd(res,n-2);
writeln(res div g,'/',(n-2) div g);
end.
